Texturing a layer in an optoelectronic device for improved angle randomization of light

Abstract

Embodiments generally relate to optoelectronic devices and more specifically, to textured layers in optoelectronic devices. In one embodiment, a method for providing a textured layer in an optoelectronic device includes depositing a first layer of a first material and depositing an island layer of a second material on the first layer. Depositing the island layer includes forming one or more islands of the second material to provide at least one textured surface of the island layer, where the textured surface is operative to cause scattering of light.

The invention claimed is: 
     
       1. A method for providing a textured layer in an optoelectronic device, the method comprising:
 depositing a first layer of a first material on a substrate, wherein the first material is a semiconductor material comprising any of: a group III-arsenide, group III-phosphide, group III-antimonide, derivatives thereof, or combinations thereof; and 
 depositing an island layer of a second material on the first layer, wherein the second material is a semiconductor and the depositing of the island layer includes:
 forming a plurality of islands of the second material to provide at least one textured surface of the island layer, wherein the plurality of islands in the island layer have variable dimensions relative to each other, and wherein the at least one textured surface is operative to cause scattering of light at randomized angles; and 
 then lifting the device off the substrate, wherein the device comprises the first layer and the island layer. 
 
 
     
     
       2. The method of  claim 1  wherein the plurality of islands are formed using a Stranski-Krastanov process. 
     
     
       3. The method of  claim 1  wherein the plurality of islands are formed using a Volmer-Weber process. 
     
     
       4. The method of  claim 1  wherein the second material is transparent. 
     
     
       5. The method of  claim 1  further comprising depositing a metal reflective layer over the island layer. 
     
     
       6. The method of  claim 1  wherein the textured layer is a back reflector layer positioned further from the front of the optoelectronic device than a p-n junction of the optoelectronic device. 
     
     
       7. The method of  claim 1  wherein the formation of the plurality of islands is controlled at least in part by a lattice mismatch between the first material and the second material. 
     
     
       8. The method of  claim 1  wherein the second includes at least one of the group consisting of: gallium, aluminum, indium, phosphorus, nitrogen, antimony, and arsenic. 
     
     
       9. The method of  claim 1  wherein the second material has a larger band gap than the first material. 
     
     
       10. The method of  claim 1  further comprising depositing a third layer of a third material on the island layer, wherein the third layer further comprises any of a dielectric layer, a semiconductor contact layer, a transparent conducting oxide layer, an anti-reflective coating, or a combination thereof. 
     
     
       11. The method of  claim 10  further comprising depositing a metal reflective layer over the third layer. 
     
     
       12. The method of  claim 10 , wherein the third layer is electrically conductive. 
     
     
       13. The method of  claim 11 , wherein the third layer is provided with apertures allowing a conductive contact between the metal reflective layer and the island layer or the first layer. 
     
     
       14. The method of  claim 10  wherein the textured layer is a back reflector layer positioned further from the front of the optoelectronic device than a p-n junction of the optoelectronic device. 
     
     
       15. The method of  claim 10  wherein the formation of the one or more islands is controlled at least in part by a lattice mismatch between the first material and the second material. 
     
     
       16. The method of  claim 10  wherein the second material includes at least one from the group consisting of: gallium, aluminum, indium, phosphorus, nitrogen, antimony, and arsenic. 
     
     
       17. The method of  claim 10  wherein the second material has a larger band gap than the first material. 
     
     
       18. The method of  claim 10  wherein depositing the third layer of a third material further comprises:
 sequentially depositing a semiconductor contact layer over the island layer; and 
 depositing a dielectric layer over the semiconductor contact layer. 
 
     
     
       19. The method of  claim 18  further comprising depositing a metal reflective layer over the third layer. 
     
     
       20. The method of  claim 19 , wherein the dielectric layer is provided with apertures allowing a conductive contact between the metal reflective layer and the semiconductor contact layer, the island layer, or the first layer. 
     
     
       21. A textured layer in an optoelectronic device, the textured layer fabricated using the process of  claim 1 . 
     
     
       22. A textured layer in an optoelectronic device, the textured layer fabricated using the process of  claim 10 . 
     
     
       23. A method for providing an optoelectronic device, the method comprising:
 depositing a base layer; 
 depositing an emitter layer; 
 depositing a first layer of a first material over the emitter layer and the base layer, wherein the first material is a semiconductor comprising any of: a group III-arsenide, group III-phosphide, group III-antimonide, derivatives thereof, or combinations thereof; 
 depositing an island layer of a second material on the first layer, wherein the second material is a semiconductor and the depositing of the island layer includes forming a plurality of islands of the second material to provide at least one textured surface of the island layer, wherein the plurality of islands in the island layer have variable dimensions relative to each other, and wherein the at least one textured surface is operative to cause scattering of light at randomized angles; and 
 lifting the device off the substrate, wherein the device comprises the base layer, the emitter layer, the first layer and the island layer. 
 
     
     
       24. The method of  claim 1  wherein the second material is a p-doped semiconductor having a doping concentration in the range of about 1×10 17  cm −3  to about 2×10 19  cm −3 .